Method and apparatus for packaging



1962 H. M. FORMAN ETAL 5 27 METHOD AND APPARATUS FOR PACKAGING 2 Sheets-Sheet 1 Filed March 6, 1961 1962 H. M. FORMAN ETAL 3,058,273

METHOD AND APPARATUS FOR PACKAGING 2 Sheets-Sheet 2 Filed March 6, 1961 III/ III/ll States The present invention relates to processes of packaging and devices for packaging articles in tubular wrapping material, suitably tubular plastic material such as polyethylene.

A purpose of the invention is to permit mechanically spreading of a tubular wrapping material, which initially goes to the point of use collapsed.

A further purpose is to spread tubular wrapping material reliably to the same cross section each time a package is made.

A further purpose is to provide a floating expander or spreader inside the tubular wrapping material which is anchored through the wall of the moving film of tubular wrapping material so that it will not travel as the wrapping material advances.

A further purpose is to guide and restrain the tubular wrapping material on the outside while spreading it on the inside.

A further purpose is to provide, on the spreading means, rails or other supports for an article being packaged.

A further purpose is to provide on the spreading means an adjustable limiter to establish the proper relation of the package with the wrapping material.

A further purpose is to make provision for cutting the wrapping material behind the package after the package has been withdrawn and the tubular Wrapping material advanced beyond the spreader.

Further purposes appear in the specification and in the claims.

In the drawings we have chosen to illustrate one only of the numerous embodiments in which the invention may appear, selecting the form shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

FIGURE 1 is a fragmentary top plan view of the packaging device of the invention.

FIGURE 2 is a section of FIGURE 1 on the line 22.

FIGURES 3 is an enlarged section of FIGURE 1 on the line 3-3.

FIGURE 4 is a perspective of the device of the invention with the tubular wrapping material largely broken away.

FIGURE 5 is an enlarged fragmentary section of FIG- URE 1 on the line 55.

FIGURE 6 is a perspective showing the device in operation and illustrating the hands of the operator.

Describing in illustration but not in limitation and referring to the drawings:

Extensive use is being made in the art of tubular wrapping material such as tubular transparent plastic like polyethylene, preferably thermoplastic, which is employed for packaging foods and the like, and after packaging is caused to grip the material packaged by shrinkage obtained by heat.

The procedure for packaging articles with this tubular plastic (preferably thermoplastic) material is tedious, because it requires that the operator spread the collapsed tube of plastic and pull it around the article or place the article inside the spread tube, depending on conditions of relative humidity and electrostatic charge. The hand manipulation may be more or less tedious.

By the present invention it is possible to greatly simplify the packaging operation, reduce the time and reduce atenr ice 3,058,273 Patented Oct. 16, 1962 the care required by the operator, and make the job less exacting.

Accordingly, much higher production rates can be obtained, under a wide variety of operating conditions.

In accordance with the invention, a spreader or expander, which is sometimes called a sled or boat, is placed inside the tubular wrapping material and anchored in space through the wall of the tubular packaging material so that it can perform its function of spreading and not be displaced when the tubular wrapping material advances.

The effect is, therefore, that a reliable cross sectional contour can be established of the tubular wrapping material at a point at which the article to be packaged can be inserted and even guided on the spreader.

When the tubular wrapping material advances, the article to be packaged also will suitably advance and the tubular wrapping material is cut off behind the article, leaving the tubular wrapping material in condition to receive a new article.

Considering now the drawings in detail, we illustrate a source of collapsed or flattened tubular wrapping material 20, which comes from a roll or other suitable supply, not shown, and progresses in the direction of the axis of the tube.

The tubular wrapping material as it advances encounters a spreader 21 as it advances which has rearward spaced sloping guiding surfaces 22 which tend to open up the tubular wrapping material laterally, and bottom spaced guiding surfaces 23 which tend to hold and spread the bottom of the tubular wrapping material, as well as top spaced spreading surfaces 24 suitably cushioned as by rubber or plastic covers as shown, so that the net result is to form the initial wrapping material into an open rectangular shape 25 as best seen in FIGURES 4 and 6.

At the rearward end of the spreader from the standpoint of the direction of motion of the tubular wrapping material, there are brackets 26 which supporta top ro-. tatable anchor roller 27 and a bottom rotatable anchor roller 28, each of which engages and rotates on the interior of the tubular wrapping material.

The top anchor roller 27 is prevented from moving forward in the direction of progression by roll 30 engaging the top of the tubular wrapping material at the outside and the bottom anchor roll is prevented from moving in the direction of progression by roll 31 engaging the bottom of the outside of the tubular wrapping material, while the bottom anchor roller 28 is prevented from moving rearwardly in the direction opposite to the direction of progression of the tubular wrapping material by roller 32 engaging the outside of the bottom of the tubular wrapping material.

The rolls 30, 31 and 32 are all supported in a frame 33 of the packaging machine.

The anchor rolls 27 and 28 are too widely spaced at their opposite sides to move forward between rolls 30 and 31 and since roll 32 is behind roll 28 the anchor rolls likewise are not able to move backward.

At a more forward position than the roll 31 the bottom of the tubular wrapping material is expanded by roll 34- supported in the housing.

The outsides of the sides of the tubular wrapping material is expanded and guided and restrained and the expansion is laterally restrained by rollers 35 rotatably mounted on the housing.

The spreader at its forward end has angle rails 36 which position and guide an article 37 to be wrapped, in this case shown as fruit or vegetables in a suitable carrier box.

The proper position of the article to be wrapped rearwardly is determined by a stop or limiter 38 which is adjustably mounted on the spreader by screw 40 and held in nut 41 which is mounted on a plate and washer held by bolts 42 which extend through slots in the spreader and are anchored in adjustable position by wing nuts 43 so as to aid in adjustment of the stop or limiter.

After the device has functioned to permit the insertion of the article in the spread portion of the tubular wrapping material, the tubular Wrapping material is cut off as by an electrically heated hot wire 44 supplied with electric current by means not shown and mounted on insulating supports 42 on an arm 43' which is pivoted on pivot 44'. Also keyed to pivot 44' is a lever arm 45 which is slidably pivotally connected at 46 to the armature 47 of solenoid 48 which'is energized by electric circuit 50 when the article moves forward far enough to close limit switch 51.

In operation with the device threaded as shown and the tubular wrapping material passing around the spreader, the operator manually, or if desired a machine mechanically, introduces an article 37 on to the guide rails 36 of the spreader inside the spread end of the tubular wrapping material as shown in FIGURE 6.

The operator then grasps the tubular wrapping material and the article and pulls them forward to the position shown in FIGURES 1 and 2 (or if desired this may be done by machine) at which point the article is beyond cut-01f position 52, 'and then the tubular wrapping material is cut off suitably because the limit switch S1 actuates the solenoid 48 to raise the hot wire cut-ofi device. The limit switch 51 is actuated by a pivoted abutment 52 which strikes against and trips the limit switch. The limit switch is mounted adjustably on a bracket 53 from the base of the mechanism, adjustment being provided by thumb screw 54. Any other suitable limit switch mechanism may be used as desired.

The user then has the article 37 surrounded by the tubular wrapping material.

In normal practice the article thus wrapped with the ends open will be deposited on a conveyor as well known in the art, which passes through a heat tunnel or oven at a suitable temperature (which in the case of polyethylene is usually 300 to 325 F.) where the heat strikes the thermoplastic for a few seconds and causes it to shrink and tightly grip the article to be packaged. Small openings are left in the end which permit the package to breathe. This is quite desirable in packaging fruits and vegetables especially. Depending upon the length of free material left beyond the package, the end of the package can be made to heat-seal in the oven. The length of the extension of the thermoplastic film beyond the end of the package determines whether or not the end will heat-seal. When it is desired to have an open or breathable package at the end, the extension of the end of the thermoplastic film beyond the package should be approximately half the height of the package. The extension can actually be between one-quarter and three-quarters of the height. Thus, if the pacakge is two inches high the extension should preferably be appproximately one inch.

On the other hand, in order to make a heat-sealed package with a closed end, the extension of the thermoplastic film beyond the end of the package should be at least as great as the heightof the package. Thus, in

4 this case if a package has a height of two inches the extension should be at least two inches.

In view of our invention and disclosure, variations and modifications to meet individual whim or particular need Will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of our invention without copying the structure shown, and we, therefore, claim all such insofar as they hall within the reasonable spirit and scope ofi our claims.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. In a packaging device having a source of collapsed tubular plastic wrapping material, spreading means lying wholly within the tubular wrapping material which expands wrapping material, means for restraining and guiding the outside of the tubular wrapping material at a position opposite the point at which it expands, and means acting through the wall of the tubular wrapping material for retaining the spreading means against moving forward as the tubular wrapping material advances.

2. A packaging device of claim 1, in which the means for retaining the spreading means comprises rollers secured to the spreading means and acting against guides on the outside of the tubular wrapping material, said rollers being spaced by a distance too great to permit them to pass between the guides.

3. A device of claim 1, in combination with guides on the spreading means to receive an article to be wrapped.

4. A device of claim 1, in combination with guides on the spreading means to support an article to be wrapped, and a limiter to position the article to be wrapped against moving too far in the direction opposite to the direction of motion of the tubular wrapping material.

5. A device of claim 1, in combination with means acting beyond the spreading means for cutting off the tubular wrapping material.

6. A device of claim 1, having means behind the means for retaining the spreading means to restrain the spreading means against moving rearwardly.

7. The method of packaging articles in wrappers of plastic tubing, which comprises progressing a collapsed plastic tube axially, spreading the collapsed plastic tube entirely from the inside of the tube by mechanical means at a position in space along the line of progression of the plastic tube which remains unchanged as the tube advances, concurrently guiding and restraining the outside of the expanded tube at the position at which the tube is expanded, introducing an article to be packaged into the expanded tube, cutting cit the expanded tube rearward in the direction of the tube progression from the article to be packaged, leaving a relatively long extension of the tubular wrapping material at the ends of the package, and heating the tubular wrapping material to an elevated temperature and thereby causing the ends to heat seal.

References Cited in the file of this patent UNITED STATES PATENTS 2,737,000 McCargar Mar. 6, 1956 2,847,806 Wang Aug. 19, 1958 2,878,628 Curry Mar. 24, 1959 2,904,943 Dreyfus et al Sept. 22, 1959 2,914,893 Berst Dec. 1, 1959 

